Production of cyanine dyestuffs



Patented May 13, 1952 2,596,776 PRODUCTION OF CYANINE :DYESTUFES JohnDavid Kendall and John Raymond Majer, Ilford, England, assignors' toIlfo'rd Limited, Ilford, England, a British company No Drawing.Application February 27, 1 947,Se-

rial N0. 731,400. In Great Britain March 1,

This invention relates to the production oi dyestuffs and particularlyto the production oi dyestuffs of the neocyanine type which aresensitising dyes for photographic silver halide emulsions.

Though the dyestuff neocyanine was first isolated in 1925 andimprovements in the method of productionhave been proposed at intervalssince that date, the various investigators have hitherto only been ableto produce neocyanines in which the three heterocycli'c nuclei are ofthe same type, e. g. all quinoline nuclei or all benzthiazole nuclei.The present invention provides a new method for the production of theneocyanine type dye wherein the three nuclei'may be allof the same type,or one of them may difier from the other two, or allthree may bedifferent from one another. 2

According to this invention dyestuffs are obtained by reacting acarbocyanine of the-general whereflih and=-D2 are the same ordifierentqand are residues of 5-membered' or Ggmembered heteroe cyclicnuclei, X is an acid radile, R1 and R4 are the same or, different an,.are alley-1101' aralkyl groups (including hydroxyalkyl orhydroxyaralkyl groups), R2 and Raare thesame or diiferent and arehydrogen atoms or alkyl or aralkyl groups, and n is; nought or one, withatrithio orthoformic ester of the formula 7 l ,./SR5' j-H -G s R6 5,

H J where R5. R6 and R7 are alkyl oraralkyl groups, and a compound ofthe general formula:

Y where D3 is the residue of a fi-membered (n 6- membered heterocyclicnucleus which may be the same as or different from D1 or D2, Rais' analkyl or aralkyl group (including an hydroxyalkyl or hydroxyaralkylgroup) Y is an acid radicle which may be the same as or different fromthe radicle X, R9 is an alkyl or aralkyl group or a. hydrogen atom, andm is nought or one, the reaction being effected in the presence of acondensing agent which will remove the compounds R5SH, RGSH and R7SHfrom the reaction medium; "6. by at- SOrptiOn orJreactiOn' therewith. r..7

I 35 atom linked to R3.

dfilaims. (01 wo -240.1) 7 l i During the condensation the threemolecules RsSH, Re'SH and RvSI-I, which will generally be identical, aresplit out yielding a product of the probable formula:

While the groupsRrBA and R8 are shown in this product as though they hadthe same significance as that given above, it will be appreciated thatif any of them were hydroxyalkyl, or hydroxyaralkyl groups in theoriginal compounds, such hydroxy groups may be converted into othergroups, e. e. acetoxy groups, in the course of the reaction.

There are, however, several indeterminate factors in this generalformula which is set out only as an indication of the general type ofproduct. Thus it is conceivable that some re-arr'angemeht of themolecule may take place. Further,"where D1 and D2 are different from oneanother and R3 is a hydrogen atom, it is uncertain whether the linkageto then"; nucleus is effected on the carbon atom as shown in the formulaor on the carbon Where the rings (and ring substituents) of which D1 andD2 form part are the same, however, the products will be identicalwhichever is the position of linkage.

The heterocyclic nuclei of which the residues D1, D2 and Da'are shownmay be any 5-membered or 6-membered heterocyclic nitrogen nuclei of thetypes common in, cyanine dyes, e; g. thiazoles, oxacoles,selenazoles'and their polycyclic homologue's such as those of thebenzene, naphthalene, 4 acenaphthene' and anthracene series, pyridineandits polycyclic homologue's such as quin'oline and '.,a;- and finaph'thaquinolines, lepidines, in-' do1enines,-'dia zines (e. g. thiofle' diazole), exam- I lines 'thiazolines and selenazolines. The poly-50 cycliocompounds of these series may also be sub- 'stituted in thecarbocyclic rings with one or more the groups R2, R3 and R9 where theselatter are not hydrogen atoms, are preferably lower alkyl groups, i. e.containing up to 4 carbon atoms, but they may be higher alkyl groups oraralkyl groups such as benzyl or naphthylmethyl.

The acid radicles X and Y may be, for example, halide ions, e. g.chloride, bromide or iodide, or alkyl sulphate, p-toluene sulphonate orperchlorate ions.

The trithio orthoformic ester may be a methyl ester of trithioorthoformic' acid or a higher homologue. The ester groups are not ofespecial importance since they do not appear in the final product, andfor this reason it is preferred to use ethyl esters, i. e. compounds inwhich R5, R6 and R7 are all ethyl groups, since the ethyl mercaptanformed during the condensation may be most readily absorbed. However, asalready indicated the ester groups may be other alkyl or aralkyl groups,e. g. benzyl groups.

In most cases the reaction can conveniently be effected by heating thereagents together in the presence of acetic anhydride since thatcompound forms an excellent absorbing medium for the mercaptan formedduring the reaction. However, in cases where the original reagents arelikely to be affected by the use of acetic anhydride, a less drasticcondensing agent may be employed, e. g. acetic acid or a mixture ofacetic acid and succinic acid. Higher fatty acid anhydrides may be used,and in general it may be stated that any acid condensing agent may beemployed, the selection being governed by the particular reagents underconsideration.

The following examples, in which the parts given are all by weight, willserve to illustrate the invention:

Example 1 Preparation of the compound of the probable Two parts of1.1'-diethyl thiocarbocyanine iodide weremixed with 1.2 parts of2-methyl benzthiazole methiodide and dissolved in a mixture of 0.8 partof triethyl trithio orthoformate and 110 parts of acetic anhydride. Thesolution was boiled for one hour and gradually changed in colour frommagenta to deep blue while a green precipitate formed. This was filtered'off and recrystallised from methyl alcohol solution 4 Example 2Preparation of the compound of the probable formula:

S o-c 05.. 7 CH=CH N/ CE: I

The procedure of Example 1 was followed using 2.5 parts of l.1'-diethylthiocarbocyanine iodide and 1.5 parts of p-toluquinaldine methiodide,and boiling for two hours, other conditions remaining the same. Theproduct was obtained as-dark green crystals with a bronze lustre,melting at 221 C. with decomposition.

The above dyestuff, included in a gelatino silver iodobromide emulsion,imparts a band of sensitivity with a maximum at 6000 A.

Example 3 Preparation of the compound of the probable formula: V

The procedure of Example 1 was followed using 2.5- partsofi;l.1'-diethyl thiocarbocyanine iodide and 1.5 parts of 2-methylbenzoxazole ethiodide, and boiling for two hours, the other conditionsremaining the same. The product was obtained as grass-green crystals, m.pt. 222 C.

The above dyestuif, included in a gelatino silver iodobromide emulsion,imparts a band of sensitivity extending to 6000 A.

Example 4 Preparation of the compound of the probable formula:

CH=CH N l The procedure of Example 1 was followed using 2.5 parts of1.1'-diethyl' 4.4'-dlmethy1 oxacarbo'cyanineiodide and 1.5 parts ofiii-naphthaquinaldine ethiodide, and boiling for two hours,

the other conditions remaining the same. The- Example 5 Preparation ofthe compound of the probable formula:

Example 6 Preparation of the compound of the probable formula:

The procedure of Example 1 was followed using 3 parts of 1.1'-diethyl3.4.3".4'-dibenzthiocarbocyanine iodide and 1.73 parts of 2-methyl4.5-dioxymethylene benzthiazole ethiodide, other conditions remainingunchanged. The dye was obtained as a dark green powder, 111. pt. 227 C.The above dyestuff, included in a gelatino silver iodobromide emulsion,imparts a band of sensitivity extending to 7200 A. with a maximumatseooki '6 Example 7 Preparation of the compound of the formula:

1.5 parts of 1.1'-diethyl selenocarbocyanine iodide and 1 part ofquinaldine ethiodide were dissolved in av mixture of 0.6 part oftriethyl trithio orthoformate and 55 parts of acetic anhydride. Thesolution was refluxed for two hours, cooled and the separated dyefiltered off and recrystallised from methyl alcohol'solution. It wasobtained as metallic green needles, m pt. 218 C. with decomposition.

The above dyestufi', included in a gelatino silver iodobromide emulsion,imparts a band of sensitivity with a maximum at 6200 A.

- Example 8 I Preparation of the compound of the probable formula:

The procedure of Example 1 was followed using 2.5 parts of 1.1-diethylthiocarbocyanine iodide and 1.5 parts of 2-methyl-N-ethyl benzimidazoleethiodide, the quantities of other reagents remaining unchanged. Afterrefluxing for two hours and cooling, some of the original dye separatedout and this was filtered off and rejected. The filtrate was evaporatedto small bulk when the required dye separated as a brown solid, m. pt.C. with decomposition.

The above dyestuiiincluded in a gelatino silver iodobromid'e emulsion,imparts a band of sensitivity extending to 6200 A. with a' maximum at6000 A.

Example 9 Preparation of the compound of the probable formula:

probable The procedure offExample 1 was followed using 2.5 parts of1.1'-diethyl thiocarbocyanine iodide and 1.6 parts of 2.3.3'.6tetramethyl indolenine methiodide. After boiling the solution was cooledand diluted with diethyl ether whereupon the desired dye separated as agreen solid,

m. pt. 170 C.

The above dyestufi, included in a gelatino silver iodobromide emulsion,imparts a band of sensitivity with a maximum at 6000 A.

Example 10 Preparation of the compound of the probable formula:

2.5 parts of indocarbocyanine was mixed with 1.67 parts of2-methyl-5-chlor benzthiazole ethiodide and dissolved in a mixture of 51parts of propionic anhydride and 0.8 parts of triethyl trithioorthoformate. After boiling for two hours a green powder separated fromsolution. This was filtered oif and recrystallised from methyl alcoholto yield the desired dye as green crystals, m. pt. 236 C. withdecomposition.

The above dyestuif, included, in a gelatino silver iodobromide emulsion,imparts a band of sensitivity with a maximum at 6000 A.

\ V Example 11 Preparationof the compound of the probable formulae:-

2.65 'parts of 1-methyl-1'ethyl-5ethoxy indoxacarbocyanine iodide wasmixed with 1.5 parts 8 of,2.5- dimethy1 benzoxazole ethiodide and dissolved in a mixture of 0.8 part of triethyl trithio orthoformate and 66parts of acetic anhydride.

The solution was boiled for two hours, and the acetic anhydride thenremoved under reduced pressure. The residue was dissolved in methylalcohol and diethyl ether added, whereupon the dye separated as a dark.brown powder, m. pt. 127 C. with rapid decomposition.

The above dyestufi, included in a gelatino silver iodobromide emulsion,imparts a band of sensitivity with a maximum at 5800 A.

Example 12 Preparation of the compound of the probable formula:

\ aha 2.5 parts of 1.1'-diethyl thiocarbocyanine iodide was mixed with1.6 parts of 2.3.3 trimethyl indolem'ne methiodide and dissolved in amixture of 0.8 part of triethyl trithio orthoformate and parts of aceticanhydride. The solution was boiled for two hours and then poured intohot water containing a trace of pyridine. The product separated as a tarwhich, after crystallisation from methyl alcohol, yielded the solid dye,m. pt. 178 C.

The above dyestufi, included in a gelatino silver iodobromide emulsion,imparts a band of sensitivity with a maximum at 6000 A.

Example 13 Preparation of the compound of the probable formula:

The ,dye sepa-' .9 Example 14 Example 16 I Preparation. of th cqmpqundof t pmbabh I .Preparation of the compound of the probable formula: a Aformula: I

The procedure of Example 1 was followed using 2.5 parts of 3:3-diethyl6:6'-dimethoxy oxacarbocyanine iodide and 1.5 parts of- 2 :4'-dimethy1quinoline methiodide. the other conditions remaining unchanged. The dyewas obtained as v a v, green needlesjm. pt. 193 C. with decomposition.The procedure of Example 1 was followed us"- The above dyestufi,included in a gelatino siling 3.0 parts of 1.1'diethyl thiooarbocyaninever iodo-bro'mide emulsion; imparts a band of iodide, 1.6 parts of2-methyl benzthiazole benzyl sensitivity extending to 7200 A.

br de. 0-8 Part of trim thyl tr tb o ortho o Analysis for iodine gavethe figure 31.85%, the mate and Parts Of acetlfl J I -f on 6001-compound of the above formula requiring 32.07 ing the boiled solutionthe dye separated, and

after crystallisation from methyl alcohol solution Example 17 wasobtained as bronze crystals, m. pt. 238 C.

I Preparation of the compound of the probable Example I5 formula:

CH! CH:

Preparation of the compound of the probable formulae- O c H 0- CH .2 5 OC-Z=C'BCH=C/ O a I Y .40 v N fHa \I l/S\ (EH:

N on \I The procedure of Example 1 was followed using 5 2.65 parts of1:3:3'-trimethyl'3'-ethyl fi-ethoxy indoxacarbocyanine iodide and 1.5parts of 2- h p du f E mple I w f l ed us methyl e-etnox benzthiazoleethiodide, other p fiszof 1.6-dimethy1-1- yl thioquinooarconditionsremaining unchanged. The dye was bocy iodide and Pa ts Of Z-methylbenzobtained as green needles from methanol, in. pt.

oxazole methiodide, other conditions remaining in C.

unchanged. The dye was obtainedj'as a brown The above .-dyestufi.included in a gelatino silsolid, m. pt. 237 C. wlthdecomposition. ;veiiodobron 1ideemulsion, imparts a band of The above dyestuff, includeda'gelatino Silrsensitivity extending to 7200 ve iodobromide e u sion. Ip r a bend. of 7, Analysis for iodine gave the figure 29.23%. the

sensitivitywith anraximum at fi iflq A. v compound of the above formula'requiring 29.0%.

11 I 12 Example 18 Example 20 Preparation of the compound of theprobable I Preparation f the compound of 1 91 formula: 5 formula: V t

i: CE; 10 2H5 I CrHs N 7 N Ca \I y C51. \I

0 The procedure of Example 1 was followed using 2.4 parts of 3:3 diethylthiaoxacarbocyanine o g=cH oH= iodide and 1.5 parts of 2 methylbenzthiazole eth- I iodide. The dye was obtained as brownish-green N g0H; 0 N needles from methanol, in. pt. 235 C. C a e 5 The abovedyestufi, included in a gelatino silver iodobromide emulsion, imparts aband of sensitivity extending to 7050 A.- Analysis for iodine gave thefigure 32.05%, the compoundof the above formula requiring 32.11%.

I Example 21' A Preparation of the compound of the probable Theprocedure of Example 1 was followed using formulae:

2.5 parts of 3:3'-dimethyl oxathiocarbocyanine .35 I v 7 CH3 CH3 iodideand 1.5 parts of 2:3:3'-trimethyl indo- C lenine methiodide. The dye wasobtained as a brown solid, m. pt. 145 C. C-C=CH CH=C/ The abovedyestuff, included in a gelatino silver iodobrpmideemulsion, imparts aband of 40 N H N sensitivity extending to 7000 A. r 211 5 Analysis foriodine gave the figure 32.8%, the I compound of the above formularequiring 33.5%.

\N Example 19 A. CE; \I

Preparation of the compound of the probable or formula: CH: CH:

\ -CH: do 1 N\ N CzHa I 0%: \I

The procedure of Example 1 was followed The procedure of Example 1 wasfollowed using using 25 parts of 1 :3,:3 :3' tetramethyl indothiapartsof 3:3"diet1}y1 oarbocyanine iodide and 1.5 parts of 2 methyl mama and 1part of 2:6 'dlmethyl benzthlazole benzoxazole methiodide. The dye wasobtained ethiodide. The dye was obtained as bronze crysasabrown solid ptwith strong tals from methanol, in. pt. 248 C. compositionu Y l Theabove dyestufi, included in a gelatino silabove dyes'tum-mchided m tm i1ver iodobromide emulsion, imparts a band of ver 'iodobromide emu1 j 6nimparts "a d of sensitivity with a maximum at 1000 A. serisitivitywithamaximum at 6000 A.

Analysis for iodine gave the figure 29.6%, the "Analysis for j iodinefga've the figure 33%, the

compound of the above formula requiring 32.0%. compound of the aboveformula requiring 33.5%.

13 Example 22 Preparation of the compound of the probable formula:

I N Czit \I H 0 432115 l Oz I The procedure of Example 1 was followedusing 2.4 parts of 3:3 diethyl thiaoxacarbocyanine iodide and 1.4 partsof 2 methyl benzoxazole ethiodide. The dye was obtained as dark greenoctahedra from methanol, m. pt. 140 0.

Analysis for iodine gave the figure 32.73%, the compound of the aboveformula requiring 32.75%.

This dye could also be obtained by a condensation of 2.5 parts of 3:3diethyl oxacarbocyanine iodide and 1.5 parts of 2 methyl benzthiazoleethiodide.

It will be observed from the foregoing examples that some variation ismade in the quantity of acetic anhydride used. As a practical point ithas been found desirable to use the minimum quantity which is sufficientfor the reaction since this facilitates the recovery of the finaldyestufi. Although the sensitising data have been given for the use ofthe dyes in a gelatino silver iodobromide emulsion, it is to beunderstood that the dyes may be usefully included in any silver halideemulsion, e. g. silver chloride or silver bromide, and also in suchemulsions Where the binding medium is other than gelatin, e. g. a vinylpolymer.

What we claim is: a

1. A process for the production of trinuclear dyestuffs which comprisesmixing a substantially pure carbocyanine of the general formula:

where D1 and D2 are each selected from the class consisting of residuesof B-membered and 6- membered heterocyclic nitrogen nuclei, X is an acidradicle, R1 and R4 are each selected from the class consisting of alkyland benzyl groups, and n is a cardinal number from 0 to 1, with atrithio orthoformic ester of the formula:

where R5, R6 and R7 are each selected from the class consisting of alkyland aralkyl groups, and with a compound of the general formula:

5 --Da N= oH- JH ,.=c oH3 Rs Y wherein D3 is selected from the classconsisting" of residues of E-membered and G-membered heterocyclicnitrogen nuclei, R8 is selected from the class consisting of alkyl andbenzyl groups, Y is an acid radicle, and m is a cardinal number from 0to 1, heating the mixture in the presence of an acid condensing agentwhereby there are removed from the reaction medium the compounds RsSH,RsSH and RnSH formed during the condensation reaction, and separatingfrom the reaction mixture the trinuclear dyestulf formed.

2. A process according to claim 1 wherein the trithio orthoformic esteremployed is one in which the groups R5, Re and R7 are identical.

3. A process according to claim 1 wherein the trithio orthoformic esteremployed is trithio orthoformic ethyl ester.

4. A process as set forth in claim 1 wherein said ester is trithioorthoformic ethyl ester and said condensing agent is acetic anhydride.

JOHN DAVID KENDALL. JOHN RAYMOND MAJER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,166,736 White et al. July 18,1939 2,263,749 White et al. Nov. 25, 1941 2,282,115 Brooker et al. May5, 1942 2,322,015 Hamer et a1. June 15, 1943 2,340,882 Kendall Feb. 8,1944 2,342,546 Kendall Feb. 22, 1944 2,353,164 Kendall et al. July 11,1944 2,484,503 Hamer Oct. 11, 1949 OTHER REFERENCES Chemical Abstracts16, 3101 (Abstract of Brit. Med. Journal, 1922, I, 514-515) ChemicalAbstracts 19, 530 (Abstract of Proc. Roy. $00., London, 96B, 317-333,1924).

Kimura: Imperial Academy of Japan (1937), pp. 261-265.

1. A PROCESS FOR THE PRODUCTION OF TRINUCLEAR DYESTUFFS WHICH COMPRISESMIXING A SUBSTANTIALLY PURE CARBOCYANINE OF THE GENERAL FORMULA: